There are many known types of quaternary compounds or “quats” and they have been used in many fields. Quats can be tremendously useful compounds. Certain quats, however, are not particularly environmentally friendly. These quats break down very slowly and could constitute an environmental pollution. Because they have reactive nitrogen species, they can have previously unrecognized activity.
Other quats, such as ester quats, which contain ester linkages, are far more environmentally friendly in as much as they degrade much more readily. Ester quats are generally formed as mono, di, or tri esters, or a mixture of mono, di, or tri ester.
Ester quats are frequently used in laundry softeners because of their environmentally friendly properties. However, ester quats are often stable only in a relatively narrow and generally acidic range of pH. Ester quats used in laundry softeners have a generally acidic pH (pH of less than about 5.0). The ester quats used in laundry softeners are generally too acidic for use as a personal care product on the hair or skin. Ester quats are disclosed in, inter alia, U.S. Pat. Nos. 6,465,419, 6,462,014, 6,323,167, 6,037,315, 5,880,086, 5,854,201, 5,750,490, 5,681,915, and 5,463,094, and U.S. Published Patent Application No. U.S. 2003/0013627.
Certainly, compounds with improved environmental properties, improved stability in a higher pH and improved substantivity would therefore be highly desirable.